bogbeagle

There seems to be an unspoken assumption that an ignition system is necessarily advantageous.

I'm not absolutely convinced of this.

A while back, I experimented at length with an ignition system on my Enya .60. ... under conditions of petroil, glow fuel, spark ignition and augmented glow. The engine retained its standard carb.

In my opinion, that engine operated best on straight glow fuel, with glow augmentation at the very low throttle openings. That is, its operation was smoothest and most reliable under those conditions.

With the standard carb + spark ignition + petroil, the minimum idle speed was higher, the carb tuning was practically impossible and there was no improvement in power.

That's what I found after about 5 hours of bench-running. Not definitive, but it convinced me.

Might have been completely different, if I'd fitted a Walbro carb, though.



I still firmly believe that glow + pump + low-speed glow augmentation = a very reliable setup.

Granted, some engines run great even without glow augmentation; and that's a bonus.

Sport_Pilot

If you retained the same advance as gas you will see little to no increase in power and it would have to idle at a higher speed. Methanol burns slower than gasoline and the timing needs to be advanced. Partly why the glow plugs work to some extent when gas is mixed with glow, the timing is retarded, but the gas needs a retarded timing compared to glow fuel, so you end up with a wider range of timing the engine can work under.

bogbeagle

I rigged it to have easily-adjustable ignition timing ... but, tbh, it's so long ago that I forget the details.

I have it all documented on an old hard drive, somewhere. Numbers and stuff.

My dominant memory is that of surprise ... surprise that the engine performed best without the ignition system. Really didn't expect that to happen.

ThunderBoat42

My Feedback: (1)

I personally love glow. Yeah, the smell tooo. :-). Aside from difficult starting 'Testors' of poor design in the early 70's I have always has great reliable performance out of them. Low idle has never been a problem. Some don't like the oil on the plane... I don't mind it. Keeps my shop smellimg good.

MTK

I've run glow for more than 40 years of my 46 years in the hobby. I know the ins and outs of glow better than most. I loved the power/weight, the smell, the ease of starting. I hated the maintenance headaches with plugs, bearings and pump replacements. Also the occasional dead starting battery or starter and most recently the considerable cost increase in feeding the beasties.

I went all small gas (30cc to 60cc) about 5 years ago when smaller gassies really started coming into their own. Purchase cost wise they are a wash. Weightwise, they are a wash power for power and that includes the extra 4 ounces of the CDI box. Maintenance really favors the gas engines. Longevity favors the gas engines. And operating cost favors the gas engines. Ease of starting really favors today's gas engines. Super simple field manners.

I have NO intention of ever going back to glow. In addition, with the "new" plugs that don't need a CDI that some companies are playing with, there won't be any reason not to run gas. Well, gas stinks and doesn't store well; that's why I don't run anything other than Avgas in my small gassies. YMMV as always